In geo-steering or directional drilling, it is important to determine direction while drilling. Data indicative of drilling tool direction is collected from sensors on the drilling tool for various depths and at various measurement times. Such sensors may measure the local earth's magnetic field, for example. This data is stored in a field computer nearby the well site, and is often stored in another computer system in a real time operations center. In this way, experts at the real time operations center have access to the same database at the remote well site, and may provide their expertise to the analysis of sensor data from various well sites.
Magnetic storms, and other phenomenon, may affect the accuracy of the data obtained from the sensors.